NFSv4 T. Haynes Internet-Draft NetApp Intended status: Standards Track November 08, 2013 Expires: May 12, 2014 Minor versioning Rules for NFSv4 draft-haynes-nfsv4-minorversioning-00 Abstract This document specifies the minor versioning rules for NFSv4. It also specifices how those minor versioning rules may be modified. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119]. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on May 12, 2014. Copyright Notice Copyright (c) 2013 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must Haynes Expires May 12, 2014 [Page 1] Internet-Draft NFSv4 November 2013 include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2 3. Modifying the minor version rules . . . . . . . . . . . . . . 2 4. The minor versioning rules . . . . . . . . . . . . . . . . . 3 5. Security Considerations . . . . . . . . . . . . . . . . . . . 6 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 7.1. Normative References . . . . . . . . . . . . . . . . . . 6 7.2. Informative References . . . . . . . . . . . . . . . . . 6 Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 6 Appendix B. RFC Editor Notes . . . . . . . . . . . . . . . . . . 6 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6 1. Introduction To address the requirement of an NFS protocol that can evolve as the need arises, the Network File System (NFS) version 4 (NFSv4) protocol contains the rules and framework to allow for future minor changes or versioning. The base assumption with respect to minor versioning is that any future accepted minor version will be documented in one or more Standards Track RFCs. Minor version 0 of the NFSv4 protocol is represented by [RFC3530], minor version 1 by [RFC5661], and minor version 2 by [NFSv42]. The COMPOUND (see Section 14.2 of [RFC3530]) and CB_COMPOUND (see Section 15.2 of [RFC3530]) procedures support the encoding of the minor version being requested by the client. 2. Terminology A basic familarity with the NFSv4 terminology is assumed in this document, the reader is pointed to [RFC3530]. 3. Modifying the minor version rules The minor versioning rules had been being maintained inside the various Standards Track RFCs, which had the impact of the minor versioning rules being modified as needed per release of the minor versions. The rules for minor versions SHOULD stand outside the minor versions and be tracked by their own Standard Track RFCs. As such, all modifications to the minor versioning rules MUST be documented not in the minor version documents, but in Standard Track Haynes Expires May 12, 2014 [Page 2] Internet-Draft NFSv4 November 2013 RFCs which are focused entirely on the minor versioning rules themselves. 4. The minor versioning rules The following items represent the basic rules for the development of minor versions. 1. Procedures are not added or deleted. To maintain the general Remote Procedure Call (RPC) model, NFSv4 minor versions will not add to or delete procedures from the NFS program. 2. Minor versions may add operations to the COMPOUND and CB_COMPOUND procedures. The addition of operations to the COMPOUND and CB_COMPOUND procedures does not affect the RPC model. * Minor versions may append attributes to the bitmap4 that represents sets of attributes and to the fattr4 that represents sets of attribute values. This allows for the expansion of the attribute model to allow for future growth or adaptation. * Minor version X must append any new attributes after the last documented attribute. Since attribute results are specified as an opaque array of per-attribute, XDR-encoded results, the complexity of adding new attributes in the midst of the current definitions would be too burdensome. 3. Minor versions must not modify the structure of an existing operation's arguments or results. Again, the complexity of handling multiple structure definitions for a single operation is too burdensome. New operations should be added instead of modifying existing structures for a minor version. This rule does not preclude the following adaptations in a minor version: Haynes Expires May 12, 2014 [Page 3] Internet-Draft NFSv4 November 2013 * adding bits to flag fields, such as new attributes to GETATTR's bitmap4 data type, and providing corresponding variants of opaque arrays, such as a notify4 used together with such bitmaps * adding bits to existing attributes like Access Control Lists (ACL) that have flag words * extending enumerated types (including NFS4ERR_*) with new values * adding cases to a switched union 4. Note that when adding new cases to a switched union, a minor version must not make new cases be REQUIRED. While the encapsulating operation may be REQUIRED, the new cases (the specific arm of the discriminated union) is not. The error code NFS4ERR_UNION_NOTSUPP is used to notify the client when the server does not support such a case. 5. Minor versions must not modify the structure of existing attributes. 6. Minor versions must not delete operations. This prevents the potential reuse of a particular operation "slot" in a future minor version. 7. Minor versions must not delete attributes. 8. Minor versions must not delete flag bits or enumeration values. 9. Minor versions may declare an operation MUST NOT be implemented. Specifying that an operation MUST NOT be implemented is equivalent to obsoleting an operation. For the client, it means that the operation MUST NOT be sent to the server. For the server, an NFS error can be returned as opposed to "dropping" the request as an XDR decode error. This approach allows for the obsolescence of an operation while maintaining its structure so that a future minor version can reintroduce the operation. 1. Minor versions may declare that an attribute MUST NOT be implemented. 2. Minor versions may declare that a flag bit or enumeration value MUST NOT be implemented. Haynes Expires May 12, 2014 [Page 4] Internet-Draft NFSv4 November 2013 10. Minor versions may declare an operation to be OBSOLESCENT, which indicates an intention to remove the operation (i.e., make it MANDATORY TO NOT implement) in a subsequent minor version. Such labeling is separate from the question of whether the operation is REQUIRED or RECOMMENDED or OPTIONAL in the current minor version. An operation may be both REQUIRED for the given minor version and marked OBSOLESCENT, with the expectation that it will be MANDATORY TO NOT implement in the next (or other subsequent) minor version. 11. Note that the early notification of operation obsolescence is put in place to mitigate the effects of design and implementation mistakes, and to allow protocol development to adapt to unexpected changes in the pace of implementation. Even if an operation is marked OBSOLESCENT in a given minor version, it may end up not being marked MANDATORY TO NOT implement in the next minor version. In unusual circumstances, it might not be marked OBSOLESCENT in a subsequent minor version, and never become MANDATORY TO NOT implement. 12. Minor versions may downgrade features from REQUIRED to RECOMMENDED, from RECOMMENDED to OPTIONAL, or from OPTIONAL to MANDATORY TO NOT implement. Also, if a feature was marked as OBSOLESCENT in the prior minor version, it may be downgraded from REQUIRED to OPTIONAL from RECOMMENDED to MANDATORY TO NOT implement, or from REQUIRED to MANDATORY TO NOT implement. 13. Minor versions may upgrade features from OPTIONAL to RECOMMENDED, or RECOMMENDED to REQUIRED. Also, if a feature was marked as OBSOLESCENT in the prior minor version, it may be upgraded to not be OBSOLESCENT. 14. A client and server that support minor version X SHOULD support minor versions 0 through X-1 as well. 15. Except for infrastructural changes, a minor version must not introduce REQUIRED new features. This rule allows for the introduction of new functionality and forces the use of implementation experience before designating a feature as REQUIRED. On the other hand, some classes of features are infrastructural and have broad effects. Allowing infrastructural features to be RECOMMENDED or OPTIONAL complicates implementation of the minor version. Haynes Expires May 12, 2014 [Page 5] Internet-Draft NFSv4 November 2013 16. A client MUST NOT attempt to use a stateid, filehandle, or similar returned object from the COMPOUND procedure with minor version X for another COMPOUND procedure with minor version Y, where X != Y. 5. Security Considerations There are no security considerations in this document. 6. IANA Considerations There are no IANA considerations in this document. 7. References 7.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", March 1997. [RFC3530] Shepler, S., Callaghan, B., Robinson, D., Thurlow, R., Beame, C., Eisler, M., and D. Noveck, "Network File System (NFS) version 4 Protocol", RFC 3530, April 2003. [RFC5661] Shepler, S., Eisler, M., and D. Noveck, "Network File System (NFS) Version 4 Minor Version 1 Protocol", RFC 5661, January 2010. 7.2. Informative References [NFSv42] Haynes, T., "NFS Version 4 Minor Version 2", draft-ietf- nfsv4-minorversion2-20 (Work In Progress), August 2013. Appendix A. Acknowledgments Appendix B. RFC Editor Notes [RFC Editor: please remove this section prior to publishing this document as an RFC] [RFC Editor: prior to publishing this document as an RFC, please replace all occurrences of RFCTBD10 with RFCxxxx where xxxx is the RFC number of this document] Author's Address Haynes Expires May 12, 2014 [Page 6] Internet-Draft NFSv4 November 2013 Thomas Haynes NetApp 495 E Java Dr Sunnyvale, CA 95054 USA Phone: +1 408 419 3018 Email: thomas@netapp.com Haynes Expires May 12, 2014 [Page 7]